Apparatus for the electrolytic manufacture of light metals and reaction products thereof.



E. A. ASHCROFT.

APPARATUS FOR THE ELECTROLYTIC MANUFACTURE OF LIGHT METALS AND REACTION PRODUCTS THEREOF.

APPLICATION FILED MAR. 12, 1912.

124,23%. Patented Nov. 7, 1916.

' 3 SHEETS-SHEET I.

' Av, ATTORNET s E. A. ASHCROFT. v APPARATUS FOB THE ELECTROLYTIC MANUFACTURE OF LIGHT METALS AND REACTION PRODUCTS THEREOF. APPLICATION FlLED MAR. 12. 1912.

Patented Nov. 7, 1916.

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M ATTOKNE Ys WITNESSES MM wy p z E. AzASHCROFT.

APPARATUS FOR THE ELECTROLYTIC MANUFACTURE OF LIGHT METALS AND REACTION PROOuCTs THEREOF.

APPLICATION FILED MA'R. I2. I9I2.

Patented NOV. 1916.

3 SIIEETS'SHEET 3.

llln lll' INVENTOR ATTORIYE rs EDGAR ARTHUR ASHCROFT, OF LONDON, ENGLAND.

A FTC,

APPTUS FOR THE ELECTROLYTIC MANUFACTURE OF LIGHT METALS AND REACTION PRODUCTS THEREOF.

Specification of Letters Patent.

Patented Nov. "7, 19116.

Application filed March 12, 1912. Serial No. 683,377.-

Balestrand, Sogn, Norway, electrochemical engineer, have invented new and useful Improvements in'and Apparatus for the ElectrolyticManufacture of Light Metals and Reaction Products Thereof, of which the following is a specification.

The object of my'invention is to efiect the manufacture of the class ofmetals known as light metals, and particularly sodium and potassium, or vreaction products thereof (or both) in a very efficient and economical manner. a

My invention relates more particularly to processes in which a salt of an alkali metal (or a. mixture of such salts) is electrolyzed in a first cell over a-cathode of liquid metal, the resulting alloy of the alkali metal and liquid metal constituting an anode in a second cell in which an electrolyte in accordance with the required productis employed, but it is not confined to such processes and may be utilized for any electrolytic production of light metals from fused metals and it is especially adapted for use in effecting the economical electrolysis of fused amids of the alkali metals with, or without, excess metals dissolved therein as described in my part of the anode, exist, effects equally fatal applications Ser. Nos. 683,376, 683,379.

Great difliculties have been experienced in. practice in recovering, by electrolysis alkali metals from fused metals of all kinds and more particularly isthis the case when an anode of soluble alloy is used. For instance if more than an extremely small cathode surface (or any surface in electrical contact with the cathode) be exposed in the melt no metal at all will appear while if too great a distance between cathode and anode, or too high current density at any to success will' arise. V V r In carrying out my 4 invention I have found by research that it is impossible to obtain the necessary conditions in practice without special devices in the. second cell which I now describe under two alternative methods either of which is efiective. Ac-

cording to the first of these methods, in.

regards current density and resistance, the arrangement may be such that the required product collects upon a number of small electrode parts, or points, arranged symmetrically over a given anode area, and in order to collect the product and remove it rapidly from the field of further action, a

constant flow of electrolyte in a very shallow layer over the anode is carried from a reservoir, preferably by means of a rotating worm pump, past the said small parts, or points. By this means it is practicable to remove the product of electrolysis and carry it at once out of the field of further reactionover a weir, or overflow, to a receptacle, or chamber, in which the product collects and from which it can be withdrawn by a suitably placedoverflow pipe, or be otherwise removed, for example by ladles. The electrolytereservoir may be separate from the main casting, or form part thereof. It is convenient to so direct the discharge. from the pump into the cell that rotary motion of the" electrolyte is set upand maintained. -The product being "a light metal (for instance sodium) it floats on the elec- V trolyte and remains in the upper part of the collecting chamber being there conveniently aggregated into a floating mass, while the associated electrolyte, being heavier, falls to the bottom of the said receptacle, or chamber, and by means of passages, passes back to the reservoir, thus maintaining a be artificially cooled as by,a coil of pipe 17 through which a cooling medium may be circulated. This prevents re-solutio'n of the metal and will throwout of solution again s0me of the metal which may have been dissolved in the electrolyte. The produced alkali metals may be removed continuously, or intermittently, from such outlet in any desired manner but preferably are allowed to run off continuously into a small receptacle. The said arrangement also facilitates the automatic separation of any small quantities of impurities (such as lead) which may be deposited with the alkali metal by disposition of the parts only very inefiicient electrolysis takes place. Iments which I have made have established Extensive experi.

the practical advantages of this arran ement over any other. The cathode is preferably constituted by small rods (preferably of nickel) of about 10 millimeters diameter brought to a conical and rounded end (an inverted parabola), or flat, and carried by a plate (preferably of copper) provided with means by which the position of the cathode can be adjusted to regulate its distance from the anode and the extent of surface in contact with the electrolyte. The overflow is preferably arranged at the center of the cell,

and the small rods of the cathode are pref erably arranged in circumferential rows. .Themetal which .collects at the top of the receptacle into which theoverflow takes place can be drawn ofi by a pipe projecting into the upper part of the said receptacle, or by other suitable means, such for instance 'as ladles. If the produced, or dissolved,

metal be reacted in situ the derived product, instead of the metal, is drawn oil by the overflow pipe. Such derived products may, for example, be amid, cyanamid, cyanid, or hydrate.

Other forms of cell embodying the same leading principles may be employed for carrying out my invention, for instance I may use a rectangular cell with the weir, or overflow, and receptacle at one end and the electrolyteainlet at the other end, the cathode parts being disposed in rows to suitably.

equalize the distribution of the current over the anode surface. The electrolyte reservoir, when,a derivative of the alkali metal is required, is provided with means for introducing the necessary reagent, or reagents, (for instance ammoma, or ammonia and carbon, benzol, or other hydrocarbon, or

' dicyan-diamid, trimethyl-amin, hydrocyanic acid, or the like) and with an outlet from whichthe derivatives can be drawn off from the reservoir, or from the receptacle, as required. An outlet is provided from which the produced gases pass off, these being conducted preferably first to the interior of the second cell and finally to an outlet in the center of that cell so that the gaseous products (for instance hydrogen, or hydrogen and ammonia gas,) Wlll ma1nta1n an atmosphere of such gas, orgases, 1n the said cell and may, in certain gases, promote further reactions. The second cell is of course provided with inlet and outlet passages for the circulating alloy constituting the anode.

means but Iprefer the means described under my application Ser. No. 683,375. When alkali amid, or other compound, is electro- -lyzed an insoluble anode of nickel, or steel,

may be used and special precautions as to temperature and other conditions are taken as described under my application Ser. No. 683,379.

Figures .1 and 2 of 'the' accompanying drawings represent in longitudinal vertical section and plan, respectively, a second cell in position together with a first cell and common alloy base and reservoir for continuous production of the. desired product, the said first cell being of the type described under my application Ser. No. 683,37 5; Fig. 3 is a vertical section of a modified form of the secondary cells in, which modification the reservoir is arranged separately of the secondary cell, but suitably connected thereto.

1 represents the first cell and 2, the second cell containing the alloy 3, and theelectrolyte 4, in a thin layer, thereon.

5 are the cathoderods.

6, is the alloy pump. 1

7 is the reservoir for electrolyte which reservoir constitutes also the pump chamber, and is shown as being within the cell 2, and 8 are the circulating passages and collecting chamber constituting also a part of the reservoir of electrolyte.

9 is the weir over which the electrolyte flows.

10 is the pump for circulating the electrolyte which is discharged against the cell.

11 is the overflow for alkali metal, and 12.

dimensions. It is connected-to the pump 10,

and to the collecting chamber below the weir 9, by means of pipes8 and 13, and a gas pipe '14:, connects the free space in the reservoir to that in the cell 2, and permits the free passage of hydrogen, ammonia, or the like.

In the second of the aforesaid methods which I may employ, for effecting the same.

, curved plate 15, so that rotary motion of the electrolyte is set up and maintained in the dispensed with. The necessary restriction of the cathode area immersed in the electrolyte and the convenient collection of the produced metal, or other product, are obtained in any suitable way.

Theaforesaid restriction of the area of the immersed cathode is necessary for successful working in such a process and the mechanical and electrical constants of the known metals which can be employed for the cathode (for example, copper, nickel, and the like) are such that the desired result can only be obtained by one, or other, of the hereinbefore described means.

In the first described means the circulating reservoir 7 may be either inside the cell 2, as illustrated in Fig. 1,'(WhlCl1 arrangement is convenient when producing metals with a high melting electrolyte such as cyanid or the like) or exterior to the cell, as

illustrated in Fig. 3, which is convenient.

when using a low melting electrolyte such as amid. or caustic alkali. I In the second described means the introduced gas may be either an inert gas such as hydrogen (forexample when metallic prod-' ucts are required), or an active gas such as ammonia, or nitrogenous, or carbonaceous, gas such as benzol, trimethylamin,HCN, or steam, or the like, or any, or all, of such agents which will react with the produced nascent metal producing the desired derivative cyanid, cyanamid, amid, or hydrate,

It will be understood that my invention can be employed for the obtainment of alkali metals, or derivatives thereof, (or both such metals and derivatives) from alloys of such metals, with other metals (for instance with lead) however such alloys may have been obtained, or it can be employed for the electrolytic production of alkali metals from electrolytes such amids, cyanids, and the like, using suitably disposed insoluble anodes.

It will also be understood that the hereinbefore described process may be usefully combined in various ways with the processes described under my applications Ser. Nos. 683,375; 683,376; 683,378 and 683,379, according to t e final products required and economical conditions generally.

In the following claims the expression alkali metal products includes alkali metals themselves as well as reaction products therefrom.

What I claim is f 1. An electrolytic apparatus of the character described having only an extremely small cathode area exposed in the electrolyte and in close proximity to the anode, and means for circulating the electrolyte in a thin layer over the surface of the anode.

2. An electrolytic apparatus of the character described having only an extremely small cathode area. exposed in the electrolyte and in close proximity to the anode, an

overflow chamber for the electrolyte and a acter described having only an extremely small cathode area exposed in the electrolyte and in close proximity to the anode, an overflow chamber for the electrolyte arranged to maintain the latter in a thin layer over the surface of the anode, and means for circulating the electrolyte from the oi'erfiow chamber to the electrolytic cell.

In testimony whereof I have signed my name to this specification inthe presence of two subscribing witnesses.

EDGAR ARTHUR ASHCROFT. Vitnesses ULYssEs J. Brwa'rnn, PAUL AuRAs. 

